The invention concerns a control arrangement for a draft tongue of a towed implement, and more particularly relates to a powered arrangement for moving the draft tongue between first, working positions and a second position, wherein the draft tongue extends transverse to the direction of operation of the implement.
U.S. Pat. No. 3,919,831 discloses a towed mowing implement with a draft tongue that can be repositioned between operating positions and a transport position by means of a hydraulic cylinder, where the tongue extends transverse to the direction of operation of the mowing implement in the transport position. In the transport position, the mowing implement can be towed on a trailer behind an agricultural tractor or the like. The repositioning movement of the hydraulic cylinder is transmitted by a scissors-like linkage, where the hydraulic cylinder is retracted in the transport position. The effect of the hydraulic motor is controlled jointly by two hydraulic cylinders so that with the full stroke of the hydraulic cylinder once the tongue reaches its transport position and the other time it does not.
U.S. Pat. No. 4,558,560 also discloses a control arrangement, that includes a hydraulic cylinder, for the pivoting of a draft tongue of a mowing implement into a transport position. The hydraulic cylinder operates upon the end of the tongue and is limited in its stroke during the operation by mechanical stops of a plate between the tongue and a frame of the mowing implement. In order to be able to completely retract the pressurized fluid motor and thereby to pivot the tongue into a transport position, the plate with the stops is pivoted into a further position.
The problem underlying the invention is seen in the fact that the cost of known devices for limiting the stroke of the hydraulic cylinder to avoid a stroke leading to the transport position is too great.
According to the present invention, there is provided an improved control for selectively limiting the stroke of an extensible and retractable hydraulic actuator, used for swinging the draft tongue of a towed implement horizontally, so that during ordinary operation of the implement, the tongue can only be swung through a working range, but which may be placed a state for permitting full extension of the actuator when it is desired that the tongue be placed in a transport position.
An object of the invention is to provide a control arrangement for an implement draft tongue, as discussed above, which is of a simple, inexpensive design.
A more specific object of the invention is to provide a control arrangement, as defined in the above object, which embodies an interrupt valve that is selectively operable to prevent full extension of the hydraulic actuator.
Yet another object of the invention is to provide a control arrangement, as defined in the immediately preceding object, wherein the interrupt valve includes an actuating device that, in an enabled condition, is operated in response to the piston rod reaching a pre-selected state of extension so as to prevent further extension. In the disclosed embodiment, this is accomplished by mounting a switching device to the piston rod, mounting the interrupt valve with its actuating device to the cylinder of the hydraulic actuator, with the actuating device being movable between a an enabled position wherein it is in the path of movement of the switching device so as to be contacted and operated thereby, and a disabled position, wherein it is moved from the path of movement of the switching device.
These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings.